A visible light source capable of a watt-class high output with strong monochromaticity is considered to be necessary in order for the realization of a large display, a high brightness display or the like. Among the three primary colors, red, green and blue, as a light source for red, a red high output semiconductor laser is applicable, which is a compact light source with high productivity used in a DVD recorder or the like. However, realization of a light source for green or blue by a semiconductor laser or the like is difficult, and a compact light source with high productivity is sought after. Particularly, the difficulty level in the realization of a light source for green is high, since there is no appropriate material for forming a semiconductor laser for obtaining a green output light.
As such a light source, a wavelength converter is realized as a low output visible light source that combines a fiber laser and a wavelength conversion element. Well known is a small light source for green or blue which uses a semiconductor laser as a light source for an excitation light that pumps a fiber laser and which uses a nonlinear optical crystal as a wavelength conversion element.
Furthermore, in a case of obtaining an output light of green or blue with a watt-class high output from such a wavelength converter, the wavelength converter comprises: a fiber laser that outputs a fundamental wave, a wavelength conversion element that converts the fundamental wave into a green laser light, and a lens that condenses the output of the fundamental wave on an end face of the wavelength conversion element.
The laser light source that realizes the green output light as described is precious and has a high value. Therefore, there is a problem that the laser light source incorporated in a laser light source application apparatus is removed for secondary utilization in other usages unforeseen by the designer.
To deal with this problem, a solid-state laser source is proposed, which has a mechanism that inserts a detrimental object (shutter) within a resonator at the same time as a laser light source is removed, resulting in blocking laser oscillation (ref. Patent Document 1). Furthermore, a projector that renders a laser diode dysfunctional is proposed, in which the projector generates a voltage surge when an attempt to remove a laser light source is made (ref. Patent Document 2).    [Patent Document 1] Japanese Laid-Open Patent Publication No. 2001-267670    [Patent Document 2] Japanese Laid-Open Patent Publication No. 2004-341210